Sub placement

I have a '01 Buick Century that I am planning on doing a little work to.  It already has component speakers in the front (which I plan on replacing with something of a little higher quality) and I believe 6x9" in the rear deck.  Lately I've been toying with some ideas for where to put subs in this car.  Being that I frequently carry things in the trunk, I do not want a large box in there.  My preference in music is mostly hard rock/metal, so I don't really need too much power.  I was thinking of utilizing some of the wasted space and doing one of two options:

1)  Make custom door panels in the rear doors to house an 8" sub in each door.  They would be as low as I could fit them in the door panel so they are basically by the passenger's feet.

2)  Put a 10"-12" sub in the rear deck between the two factory speaker holes.  Do I build a small, shallow enclosure or run a "free air" setup?

In my first vehicle, which was a hatchback, I ran (2) 12" Fosgate XLC's in a bandpass box.  Although I liked the incredibly loud bass, I just can't do it with this car since I'm now a family man.  What are the positives and negatives of my different approaches?

*bump*

I need some input on this, so I bumped it back to the top.

Do you really want to do much cutting? b/c when the sheet metal on your rear deck is cut up it's really no turning around.

were you thinking of doing the 8's, the 12" or both?